internal/postgres: log errors from deleting package_version_states
internal/postgres: log errors from deleting package_version_states

Change-Id: Ib6c36be1c493277e6581fabae464c0854075a0a7
Reviewed-on: https://team-review.git.corp.google.com/c/golang/discovery/+/720897
CI-Result: Cloud Build <ea5729d4cf3392b9d382b6ca272c65aa27554f44@system.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <e3d3698b2ccd5955e4adf250d0785062d0f9018b@google.com>

golang/pkgsite,golang/pkgsite,golang/pkgsite,golang/pkgsite